EPR studies of soybean leghemoglobin a (Lb) in the presence of perfluorophenol(PF) or paranitrophenol,(PN) and of Paramphistomum epiclitum hemoglobin have been conducted. This Hb contains two tyr residues in their distal pockets, at positions B10 and at E7. With phenols, Lb exists as high spin/low spin mixtures. The g = of 2.73, 2.26, 1.75 and 2.64, 2.22, 1.80 for the low spin forms with PF and PN, respectively. This spin mixture property is analogous to hemoproteins with known ligation such as Hbn M and Lucina pectinata HbII. The g values for the low spin form of Lb in the presence of PF resemble those resolved for the proposed hist-tyr complex of L. pectinata Hb II (2.76, 1.75), while the g values for low spin Lb in the presence of PN resemble those of the proposed OH complex of L. pectinata Hb II (2.61, 2.20, 1.82). P. epiclitumIn Hb exhibits high spin-low spin mixture at alkaline pH (9.3). The low spin forms has g values of 2.67, 2.13, 1.78. The increased anisotropy as compared to the HO complexes of L. pectinata Hb II (g=2.61, 2.20, 1.82) and myoglobin (2.55, 2.17, 1.85) suggest tyr coordination to the heme Fe. It is suggested that the E7 tyrosine of P. epiclitumIn Hb serves as an axial heme ligand.